Locally Aggressive Hepatic Echinococcosis With Colonic Involvement Requiring a Right Hemicolectomy: A Case Report and Focused Literature Review.

Echinococcosis most commonly presents as a slowly enlarging hepatic cyst, whereas extensive inflammatory extension with colonic involvement is uncommon. We report the case of an 80-year-old man who presented with abdominal pain and fever and reported having been aware of a hepatic echinococcal cyst for approximately 30 years. CT showed a giant calcified hepatic cyst containing an air-fluid level and intralesional gas, suggestive of secondary infection; intraoperative cyst-fluid culture subsequently grew Escherichia coli. Emergency laparotomy revealed dense inflammatory adherence to the transverse mesocolon and colon with obliteration of the dissection planes, necessitating right hemicolectomy with ileotransverse anastomosis, partial cyst wall excision, and drainage. Histopathology confirmed echinococcosis with extensive fibrosis, abscess formation, necrosis, and intestinal-surface involvement. The morphology raised suspicion for alveolar echinococcosis, although species-level confirmation was unavailable. The patient recovered uneventfully and received albendazole. This case highlights that chronically infected hepatic echinococcosis may mimic locally invasive disease and require adjacent-organ resection even without a demonstrable cystocolonic fistula.